Since ancient times, the anomalous occurrence of mushrooms around lightning strikes has been confirmed. Based on this phenomenon, various shiitake mushroom cultivation methods with lightning strikes using cultivation bed logs (wood) have been proposed. One remarkable related work reported that the fruiting capacity of shiitake mushrooms was significantly promoted by directly applying a high voltage to the cultivation bed log1). However, mushroom bed logs are rarely struck by lightning directly in the natural environment. Therefore, this method does not match the conditions in the natural environment. We performed lightning strike experiments using a new method that considers the natural environment. This new method delivers a thunderbolt to a lightning rod using the electric discharge created by an impulse voltage generator, but it does not apply lightening directly to the cultivation bed log. The cultivation bed logs are placed a few meters away from the lightning rod in order to replicate the natural environment. In this experiment, we compared the fruiting capacity of shiitake mushrooms with and without simulated lightning strikes. From the experimental results, in the case of simulated lightning strikes, twice the number of shiitake fruiting bodies was harvested compared with the case without simulated lightning strikes. Moreover, this result clearly specifies that even though a high voltage was not applied directly, increased production of shiitake mushrooms by lightning strikes was confirmed.